Method and apparatus for fabricating tubular units



Feb. 24, 19259 l G. w. HALDEMAN METHOD AND APPARATUS FOR FABRICATING TUBULAR UNITS v Filed-Jan. 9. 1947 United States PatentO "nice METHOD -AND APPARATUS: FOR FABRICATING 'li`UBULAR UNITS f Applieatienvranuery 9, 1947, serial No. 121,006 6 Claims.I (cl. z9-s17 This invention relates toV a novel method and means for fabricating a unit containing a plurality of substantially equidistantly spaced elements within a tube.

. More specifically, the invention comprises av novel method `and apparatus for drawing a ductile tube to contract the same around a plurality of cylindricalsubstantially non-compressible members while equidistantly spacing said members a predetermined distance from each other withinthe tube. i

The present invention relates more vparticularly tov a novel method and apparatus for fabricating composite reactive units containing is'sionable material and adapted for'utilization as Aa source of fuel for a Yself-sustaining nuclear fission cha'inreaction.4 Units of thsjtype consist of cylindrical slugs" lcontaininguranium or other iissionable `material tightly fitted withinan aluminum the die, and Fig. 4 showing the same slug afterV having passed through the die. Y

Describing the invention in detail and referring rst to Fig. 1, the `novel apparatus disclosed thereincom prises a foundation or drawbench Zand a rail or track 4 thereabove affording support for a. pair of wheels 6, the axles of which are journalled in upstanding pedestals 8 of a frame or carriage 10, said carriageV being connected by a rod 12 to a similar pedestal 14 supporting a pulling head 16 from a wheel'18 on the track 4.

The pulling head 16 grips one end of an aluminum tube 20, such as above described, filled with a plurality of cylindrical uranium slugs 22, The tube 20 is drawn throughf a die 24 to contract'the tube around the slugs into tight thermal contact therewith, the slugs 22 being i pushed through the die by a hollow pusher rod 26 connected to a travelling nut 28 threadedly engaged with a rotatable shaft 30 actuated by a gear box 32 mounted on the carriage 10. The gear box is operatively con-V nected to a gear 34 which is meshed with a rack 36 on the drawbench 2. Thus, as the pulling head 16 is moved on the advance or pulling .stroke thereof by an `associated conventional hydraulic motorv 38, the tubef 20 is tube orfcartridge, spacing :being provided between .the Y i `slugsto accommodate thermal expansion and exibility of the unit. Preferably the tube is iilled with an inert gas, such as helium, which fills the spaces between the slugs to facilitateheat conductivity fromztheislugs to the aluminum tube yor jacket lat the j spaqces between the slugs, and to displace the "atm'spherewhich" might otherwise react with the uranium slugs to form'uranium oxide and nitride, thereby creating a vacuum between the `slugs and causing thelatter to swell Vfrom thenew compounds formed. The slugs are preferably from 2 to 8 inches long with spaces therebetweenv of from 1A@ of an inch to 1A of an inch, and preferably the slugs have a diameter of about 1.4 inches with a ground finish on the cylindrical perimeter thereof to accommodate a tight fit within the aluminum tube, which preferably has an outer diameter of about 1.5 inches.

The first attempts to fabricate a unit, such as above described, by drawing the aluminum tube orV jacket onto a series of slugs by drawing the assembly through a single die, resulted in non-uniform spacing between the slugs with variances of up to' several inches. Frequently in the same tube, slug spacing was found to vary over 100 percent.

The present invention comprehends a novel method and means for producing uniform spacing between the slugs and for iilling the spaces with an inert gas, such as helium, while drawing the aluminum tube into tight thermal contact with the slugs.

The foregoing and other objects and advantages of the invention will become apparent from a consideration of the following specification and the accompanying drawings, whereinz v Fig. 1 is a somewhat diagrammatic illustration of an apparatus embodying the invention, the apparatus being shown partly in side elevation and partly Yin section; and

Figs. 2 to 4, inclusive, are diagrams showing the passage of the tube and slugs through the die to produce the desired spacing, Fig. 2 vshowing a slug entering theV drawn through the die, and the travelling nut'28 moves to the left, as seen in Fig; .1, relative to the carriage 10 so that the hollow pusher rod 26 moves to the rightat a slower rate of speed than that at which the pulling head 16 moves, thus causing the pusher rod 26 to fall back or lag with respectto the head 16 to accommodate spacing Vof the slugs 22 within the tube 20 as the latter is drawn into tight thermal contact with the slugs.

The pusher rod 26 is connected by a flexible tube 40 to a source 42 of inert gags, such as helium. Thus, the spaces between the slugs are illed with lhelium for'v the above-mentioned purposes.V

As above noted, the advance movement of the pusher Y, rod 26 tothe right, as shown in Fig. l, is preferably at a predetermined slower rate than that of the head` 16, thus accommodating equidistant lspacingof the noni-compresl` sible elements 22 within the tube20. lIf desired, th'e travelling nut 28 may be rendered inoperative, as for example, by disconnecting the gear 34 from the gear box 32 thus causing the pusher rod 26 to move on its advance stroke to the right, as seen in Fig. 1, at the same rate as the pulling head 16. This would substantially eliminate spacing between the slugs although slight spacing would be present due to stretching of the tube 20 at the right of the die 24.

Referring now to Figs. 2-4, the spacing of the slugs in the'tube is diagrammatically illustrated. Thus, in Fig. 2, slug No. 1, which has passed through the die,` is clamped by the tube and is moving with the same in the direction of the arrow at rate B, which is approximately the pulling rate of the head 16 and the rate of movement of the tube 20 at the right or exit side of the die. Slug No. 2 which is moving at rate A, the rate of movement of the pusher rod 26, is just entering the die 34 in Fig. 2. In Fig. 3, slug No. 2 has partially passed through the die and is moving with the tube at rate B, causing a space to form at 44. This space is shown fully formed in Fig. 4, whereinslug No. 3 has entered `the die and is about to move at rate B to produce a space between slug No. 3 and slug No. 4. It will be understood that the spacing between the slugs 22 is dependent upon the relative movement of the pulling head 16 and the pusher rod 26.

As above discussed in connection withFigl, the car riage 10 and the pulling head 16 are connected as by a l rod 12 so that the pusher rod 26, the head 16 and the die, Fig. 3 showing the same slug partially drawn through Y tube 20 are moved [by the hydraulic motor 38 toward the" right, as4 seen inV this ligure. Thus, althoughrthe pusher rod 26 moves towardthe right relative to the die 24, the pusher rod 26 is, in a sense, retracted from the tube 20 by relative motion with respect thereto, thus producing the before-mentioned spacing of the slugs, although the total retraction of the pusher rod 26 from the tube 20 may not Abe substantially greater than the elongation thereof `byy the drawing process. This retraction of the pusher rod 26 from' the tube 20. may, if desired, be keffectedjbyconnvecting the carriage 10 to thefdie 24 and moving these parts` to the lleft as by a hydraulic motor (not'shown) while maintaining the head 16 in a stationaryk position; .Under these conditions the od'26 would alsoI be' retracted relative to the tulbe 20, but would be moved by nut 28 toward the 'die 2,4 to diminish the distancebet'ween the rod 26 and the die 24, thereby pushing the slugs 2,2 ,through the die. Thus, it will be. understoodA that the rate at which the pusher rod 2 6 is retracted relative to the tube 20 will be less than the rate at which the tube 20 enters the die 24 regardless of Whetherthe tube is pulled through the die or the die isfpulled along the tube. In other words, as the tube is drawn Iby relative motion between the die and the t-ube, the distance between'the die and the adjacent end of the pusher rod 26 is diminished to force the slugs through the die.`

I t will be understood that the above-described method and apparatus vembodying the invention are merely -`by way of illustration and not limitation, inasmuch as various and other forms `of theV invention will be readily apparent to Vthose skilled in the art without departing from the spirit of the invention or the scope of the ap-V pended claims.

What is claimedv is Y 1. A method of fixing a plurality of members within a ductile tube in spaced relationship therein, comprising drawing'said tube intoftight engagement with said members while continuously retracting Vfrom said tube at a rate less'tharithe drawing rate an element adapted to limit movement of said members uoutwardly from said tulbe during said drawing thereof. Y

2. A method of nxing a plurality of membersl within a ductiletube. in spaced relationship therewithim coinprising inserting a group end-to-end abutting relationship with eachother, positioni'ng an element within said tubeV in abutment'with the 4 t member at one end of the group, and drawing said tube into .tight engagement with said members from the opposite end of said group while retracting said element from said tube at a rate less than the drawing rate.

3. A method of fabricating a unit wherein a ductile tube contains a plurality of., rigid members spaced by pockets of uid, comprising inserting a group of said members into said tube in end-to-end abutting relationship, positioning a rigid 'hollow element within said tube in abutment with the -member at one end of said group, and then drawing said tube into tight engagement with said members from the opposite end of said group while retracting said element from said tube at a rate less than the drawing rate, and while directing said uid into said tube through said element.

4. An apparatus for drawing a ductile tube into tight engagement with a plurality of members therein, comprising means for gripping the tulbe, die means for engaging the tube, means for moving at least one of said means with respect to the other to force said tube through said die-means, means insertable within the tube for I restricting movement of said members therein in the of said members in said tube in direction away from said die means, and means for spacing said members in said tube comprising means for withdrawing said restricting means from the tube as the latter passes' through said die means.

5. A method which comprises inserting a tube member containing a plurality of substantially non-compressible elements into Va die member and moving at least one of the members to draw the tube member into tight contact with said elements while pushing said elements toward said die member Vat a rate substantially less than the drawing rate.

6. method which comprises drawing a ductile tube into tight contact with a'plurality of substantially nonc'ompressible members therein while'pushing said mem-l bers'withn saidtube inthe direction of movement thereof.

ReferencesV Cited in the file of this patent UNITED STATES PATENTS 440,130 Bray Nov. l1, 1-890 524,507 Robertson Aug. 24, 1894 1,779,478 Leach Oct. 28, 1930 

